$GTK_IM_MODULE ignored after upgrade

[Konstantin]

After upgrade trusty → xenial, Compose key stopped producing configured through ~/.XCompose characters for GTK3 only apps. To be sure that its the GTK problem, I created a simple GTK3 window with textbox, launched it like:

 $ GTK_IM_MODULE=xim XMODIFIERS=@im=none ./a

and the textbox produces wrong characters for Compose key. (the variables are actually set globally, I wrote them here just for clarity).

XCompose works fine for all other toolkit's apps, including GTK2 and Qt ones.

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu

$ lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04

2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
$ apt-cache policy libgtk-3-0
libgtk-3-0:
  Installed: 3.18.9-1ubuntu3
  Candidate: 3.18.9-1ubuntu3
  Version table:
 *** 3.18.9-1ubuntu3 500
        500 http://ru.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

3) What you expected to happen

«Compose + - + space» would produce «— » in GTK3 apps.

4) What happened instead

«Compose + - + space» producing «~» in GTK3 apps.

[Konstantin (hi-angel-z)]

Okay, this is definitely GTK3 bug. I tried to debug GTK3, and found that in gtkimmodule.c it tries to lookup "xim" in some «contexts_hash»

   found = g_hash_table_lookup_extended (contexts_hash, *immodules_list,
      (gpointer *) &context_id, NULL);

It fails, and a bit later in the line

   return context_id ? context_id : SIMPLE_ID;

it returns "gtk-im-context-simple".

[Sebastien Bacher (seb128)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue you are reporting is an upstream one and it would be nice if somebody having it could send the bug to the developers of the software by following the instructions at https://wiki.ubuntu.com/Bugs/Upstream/GNOME. If you have done so, please tell us the number of the upstream bug (or the link), so we can add a bugwatch that will inform us about its status. Thanks in advance.

[Konstantin (hi-angel-z)]

Okay, I'll report it as I can.

[Konstantin (hi-angel-z)]

Reported the bug here https://bugzilla.gnome.org/show_bug.cgi?id=768412

[Konstantin (hi-angel-z)]

Okay, so — in short — the problem was that the command `/usr/lib/x86_64-linux-gnu/libgtk-3-0/gtk-query-immodules-3.0 --update-cache` wasn't run upon distro upgrade. Actually, I'm not sure if it's a distro bug or not, because in my case the distro-upgrade came not quite fine. I was having a PPA with latest GCC, which I didn't purge — that looks right, why would I care if I'm using a binary distro anyway? However, after upgrade Xorg didn't even start; long story short — libstdc++, for some reason, didn't have some function which some apps were using. Reinstalling to vanilla libstdc++ solved the problem. I did even see a bug about it somewhere, but can't find it. But I can assume that some apps for distro upgrade failed to run because of the library — as the bug with $GTK_IM_MODULE not the only problem I encountered here. I'm seeing things like missing tray icons, ignored preview options in Dolphin, crashing vlc, and more.